Advances in minimally invasive surgical technology could dramatically increase the number of surgeries performed in a minimally invasive manner. Minimally invasive medical techniques are aimed at reducing the amount of extraneous tissue that is damaged during diagnostic or surgical procedures, thereby reducing patient recovery time, discomfort, and deleterious side effects. The average length of a hospital stay for a standard surgery may also be shortened significantly using minimally invasive surgical techniques. Thus, an increased adoption of minimally invasive techniques could save millions of hospital days, and millions of dollars annually in hospital residency costs alone. Patient recovery times, patient discomfort, surgical side effects, and time away from work may also be reduced with minimally invasive surgery.
The most common form of minimally invasive surgery may be endoscopy. Probably the most common form of endoscopy is laparoscopy, which is minimally invasive inspection and surgery inside the abdominal cavity. In standard laparoscopic surgery, a patient""s abdomen is insufflated with gas, and cannula sleeves are passed through small (approximately xc2xd inch or less) incisions to provide entry ports for laparoscopic surgical instruments. The laparoscopic surgical instruments generally include a laparoscope (for viewing the surgical field) and working tools. The working tools are similar to those used in conventional (open) surgery, except that the working end or end effector of each tool is separated from its handle by an extension tube. As used herein, the term xe2x80x9cend effectorxe2x80x9d means the actual working part of the surgical instrument and can include clamps, graspers, scissors, staplers, and needle holders, for example. To perform surgical procedures, the surgeon passes these working tools or instruments through the cannula sleeves to an internal surgical site and manipulates them from outside the abdomen. The surgeon monitors the procedure by means of a monitor that displays an image of the surgical site taken from the laparoscope. Similar endoscopic techniques are employed in, e.g., arthroscopy, retroperitoneoscopy, pelviscopy, nephroscopy, cystoscopy, cisternoscopy, sinoscopy, hysteroscopy, urethroscopy and the like.
There are many disadvantages relating to current minimally invasive surgical (MIS) technology. For example, existing MIS instruments deny the surgeon the flexibility of tool placement found in open surgery. Most current laparoscopic tools have rigid shafts, so that it can be difficult to approach the worksite through the small incision. Additionally, the length and construction of many endoscopic instruments reduces the surgeon""s ability to feel forces exerted by tissues and organs on the end effector of the associated tool. The lack of dexterity and sensitivity of endoscopic tools is a major impediment to the expansion of minimally invasive surgery.
Minimally invasive telesurgical robotic systems are being developed to increase a surgeon""s dexterity when working within an internal surgical site, as well as to allow a surgeon to operate on a patient from a remote location. In a telesurgery system, the surgeon is often provided with an image of the surgical site at a computer workstation.
While viewing a three-dimensional image of the surgical site on a suitable viewer or display, the surgeon performs the surgical procedures on the patient by manipulating master input or control devices of the workstation. The master controls the motion of a servomechanically operated surgical instrument. During the surgical procedure, the telesurgical system can provide mechanical actuation and control of a variety of surgical instruments or tools having end effectors such as, e.g., tissue graspers, needle drivers, or the like, that perform various functions for the surgeon, e.g., holding or driving a needle, grasping a blood vessel, or dissecting tissue, or the like, in response to manipulation of the master control devices.
Some surgical tools employ a roll-pitch-yaw mechanism for providing three degrees of rotational movement to an end effector around three perpendicular axes. At about 90xc2x0 pitch, the yaw and roll rotational movements overlap, resulting in the loss of one degree of rotational movement.
The present invention is generally directed to robotic surgery methods, devices, and systems. The invention provides a minimally invasive surgical tool which operates with three degrees of rotational movement at about 90xc2x0 pitch. In particular, the surgical tool employs a roll-pitch-roll configuration in which an elongate shaft is rotatable in proximal roll, a wrist member is pivotally mounted on the working end of the elongate shaft to rotate in pitch, and an end effector is pivotally mounted on the wrist member to rotate in distal roll around the wrist roll axis of the wrist member. At about 90xc2x0 pitch, the wrist roll axis is generally perpendicular to the shaft axis of the elongate shaft. The proximal roll around the shaft roll axis and the distal roll around the wrist roll axis do not generally overlap. In some embodiments, an additional mechanism is used to actuate the end effector in yaw rotation.
In accordance to an aspect of the present invention, a minimally invasive surgical instrument comprises an elongate shaft having a working end and a shaft axis. A wrist member has a proximal portion pivotally connected to the working end to rotate relative to the working end around a pitch axis which is nonparallel to the shaft axis. An end effector is pivotally mounted on a distal portion of the wrist member to rotate around a wrist roll (distal roll) axis of the wrist member. The wrist roll axis extends between the proximal portion and the distal portion of the wrist member. The end effector may also be pivotally mounted to rotate relative to the wrist member around a yaw axis which is nonparallel to the wrist roll axis.
In some embodiments, the end effector includes an end effector base which is pivotally mounted on the distal portion of the wrist member to rotate around the distal wrist roll axis of the wrist member. The end effector includes at least one working member pivotally mounted to the end effector base to rotate around the yaw axis. The yaw axis is perpendicular to the distal wrist roll axis. The pitch axis is perpendicular to the shaft axis.
In specific embodiments, a torsion tube is coupled with the end effector base and is rotatable to turn the end effector base around the wrist roll axis of the wrist member. The torsion tube extends through an interior of the elongate shaft to a proximal end opposite from the working end of the elongate shaft. The end effector includes at least one working member pivotally mounted to the end effector base to rotate around the yaw axis. The working member of the end effector is rotatable around the yaw axis by a yaw pulley-and-cable mechanism including at least one cable extending from the working member of the end effector through an interior of the torsion tube to the proximal end of the elongate shaft. The wrist member is rotatable relative to the working end around the pitch axis by a pitch pulley-and-cable mechanism including at least one cable extending from the wrist member to the proximal end of the elongate shaft through a space inside an interior of the elongate shaft and outside of the torsion tube. The torsion tube is bendable around the pitch axis with rotation of the wrist member around the pitch axis relative to the working end.
In accordance with another aspect of the present invention, a minimally invasive surgical instrument comprises an elongate shaft having a working end and a shaft axis. A wrist member has a proximal portion pivotally connected to the working end to rotate relative to the working end around a pitch axis which is nonparallel to the shaft axis. An end effector is pivotally mounted on a distal portion of the wrist member to rotate around a distal wrist roll axis of the wrist member. The wrist roll (distal roll) axis extends between the proximal portion and the distal portion of the wrist member. A torsion tube is coupled with the end effector and is rotatable to turn the end effector around the wrist roll axis of the wrist member.
In accordance with another aspect of the invention, a method of performing minimally invasive endoscopic surgery in a body cavity of a patient comprises introducing an elongate shaft having a working end into the cavity. The elongate shaft has a proximal end and a shaft axis between the working end and the proximal end. The method further comprises rotating a wrist member pivotally coupled with the working end relative to the working end. The wrist member has a wrist roll axis. An end effector pivotally mounted on the wrist member is rotated around the wrist roll axis to position the end effector at a desired location inside the cavity, by turning a torsion tube extending through an interior of the elongate shaft to the proximal end of the elongate shaft and being coupled with the end effector.
In some method embodiments, the wrist member is rotated around a pitch axis which is perpendicular to at least one of the shaft axis and the wrist roll axis to change an angle between the wrist roll axis and the shaft axis. Rotating the wrist member around the pitch axis bends the torsion tube around the pitch axis. At least one working member of the end effector is rotated around a yaw axis nonparallel to the wrist roll axis. The elongate shaft is rotated around the shaft axis to position the end effector at the desired location inside the cavity.